Isolation and characterization of peptides with antihypertensive activity in foodstuffs

Peptidomics and molecular dynamics on bioactive peptides produced and characterized from the fermented whey of "Panchali" sheep of West India

The study assessed the peptide production by using potent Lactiplantibacillus plantarum KGL3A (MG722814) culture to ferment the sheep milk for evaluation of α-glucosidase inhibition, ACE inhibition, α-amylase inhibition, & inhibiting lipase activities. The maximal ACE inhibitory, α-amylase, α-glucosidase, & lipase inhibiting actions were 71.69 %, 71.32 %, 67.14 %, and 64.15 %, respectively, at 37 °C after 48 h. Proteolytic activity was tested at various incubation times & inoculation rates to maximise the conditions for growth and the greatest action (9.38 mg/mL) was reported at 2.5 % rate of inoculation after incubation of 48 h. The anti-diabetic as well as ACE inhibitory properties of less than 3 kDa were maximum in contrast to >3 kDa, <10 kDa, and > 10 kDa cut-off fractions. Further, when LPS stimulation is applied to RAW 267.4 macrophage cells, the overabundance generation of IL-6, IL-1β, NO, and TNF-α is greatly reduced by using KGL3A to ferment sheep milk. 2D gel electrophoresis & SDS-PAGE were utilized in relation to protein purifications. Maximum numbers of sheep milk's fermented protein bands were present, about 10 to 124 kDa by SDS-PAGE, and 38 spots of protein were discovered using 2D gel chromatography. Ultra-filtered fractions water soluble extracts (WSEs) were employed in RP-HPLC to differentiate between various peptide fractions. The peptide sequences produced were matched using the databases of AHTPDB and BIOPEP to match hypertensive peptides & antidiabetic peptides, respectively. Furthermore, the discovered peptide sequences from the fermenting sheep milk was studied due to their penchant for binding against the active locations of human bile salt activated lipase (hBAL); human maltase-glucoamylase (hMGA); human pancreatic alpha-amylase (hPAM); & human angiotensin-converting enzyme (hACE) through molecular docking.

Potential of Marine Bacterial Metalloprotease A69 in the Preparation of Peanut Peptides with Angiotensin-Converting Enzyme (ACE)-Inhibitory and Antioxidant Properties

Marine bacterial proteases have rarely been used to produce bioactive peptides, although many have been reported. This study aims to evaluate the potential of the marine bacterial metalloprotease A69 from recombinant Bacillus subtilis in the preparation of peanut peptides (PPs) with antioxidant activity and angiotensin-converting enzyme (ACE)-inhibitory activity. Based on the optimization of the hydrolysis parameters of protease A69, a process for PPs preparation was set up in which the peanut protein was hydrolyzed by A69 at 3000 U g-1 and 60 °C, pH 7.0 for 4 h. The prepared PPs exhibited a high content of peptides with molecular weights lower than 1000 Da (>80%) and 3000 Da (>95%) and contained 17 kinds of amino acids. Moreover, the PPs displayed elevated scavenging of hydroxyl radical and 1,1-diphenyl-2-picryl-hydrazyl radical, with IC50 values of 1.50 mg mL-1 and 1.66 mg mL-1, respectively, indicating the good antioxidant activity of the PPs. The PPs also showed remarkable ACE-inhibitory activity, with an IC50 value of 0.71 mg mL-1. By liquid chromatography mass spectrometry analysis, the sequences of 19 ACE inhibitory peptides and 15 antioxidant peptides were identified from the PPs. These results indicate that the prepared PPs have a good nutritional value, as well as good antioxidant and antihypertensive effects, and that the marine bacterial metalloprotease A69 has promising potential in relation to the preparation of bioactive peptides from peanut protein.

Production and characterization of anti-hypertensive and anti-diabetic peptides from fermented sheep milk with anti-inflammatory activity: in vitro and molecular docking studies

BACKGROUND

The present study aimed to evaluate the anti-hypertensive and anti-diabetic activities from biologically active peptides produced by fermented sheep milk with Lacticaseibacillus paracasei M11 (MG027695), as well as to purify and characterize the angiotensin-converting enzyme (ACE) inhibitory and anti-diabetic peptides produced from fermented sheep milk.

RESULTS

After 48 h of fermentation at 37 °C, sheep milk demonstrated significant changes in anti-diabetic effects and ACE-I effects, with inhibition percentages observed for ACE inhibition (76.32%), α-amylase (70.13%), α-glucosidase (70.11%) and lipase inhibition (68.22%). The highest level of peptides (9.77 mg mL-1) was produced by optimizing the growth conditions, which included an inoculation rate of 2.5% and a 48 h of incubation period. The comparison of molecular weight distributions among protein fractions was conducted through sodium dodecyl-sulfate polyacrylamide gel electrophoresis analysis, whereas spots were separated using 2D gel electrophoresis according to both the molecular weight and pH. Peptide characterization with ultra-filtration membranes at 3 and 10 kDa allowed the study to assess molecular weight-based separation. Nitric oxide generated by lipopolysaccharide and the secretion of pro-inflammatory cytokines in RAW 264.7 immune cells were both inhibited by sheep milk fermented with M11. Fourier-transform infrared spectroscopy was employed to assess changes in functional groups after fermentation, providing insights into the structural changes occurring during fermentation.

CONCLUSION

The present study demonstrates that fermentation with L. paracasei (M11) led to significant changes in fermented sheep milk, enhancing its bioactive properties, notably in terms of ACE inhibition and anti-diabetic activities, and the generation of peptides with bioactive properties has potential health benefits. © 2024 Society of Chemical Industry.

Peptidomics-based identification of antihypertensive and antidiabetic peptides from sheep milk fermented using Limosilactobacillus fermentum KGL4 MTCC 25515 with anti-inflammatory activity: in silico, in vitro, and molecular docking studies

This study investigated the synthesis of bioactive peptides from sheep milk through fermentation with Limosilactobacillus fermentum KGL4 MTCC 25515 strain and assessed lipase inhibition, ACE inhibition, α-glucosidase inhibition, and α-amylase inhibition activities during the fermentation process. The study observed the highest activities, reaching 74.82%, 70.02%, 72.19%, and 67.08% (lipase inhibition, ACE inhibition, α-glucosidase inhibition, and α-amylase inhibition) after 48 h at 37°C, respectively. Growth optimization experiments revealed that a 2.5% inoculation rate after 48 h of fermentation time resulted in the highest proteolytic activity at 9.88 mg/mL. Additionally, fractions with less than 3 kDa of molecular weight exhibited superior ACE-inhibition and anti-diabetic activities compared to other fractions. Fermentation of sheep milk with KGL4 led to a significant reduction in the excessive production of NO, TNF-α, IL-6, and IL-1β produced in RAW 267.4 cells upon treatment with LPS. Peptides were purified utilizing SDS-PAGE and electrophoresis on 2D gels, identifying a maximum number of proteins bands ranging 10-70 kDa. Peptide sequences were cross-referenced with AHTPDB and BIOPEP databases, confirming potential antihypertensive and antidiabetic properties. Notably, the peptide (GPFPILV) exhibited the highest HPEPDOCK score against both α-amylase and ACE.

Two novel angiotensin I-converting enzyme inhibitory peptides from garlic protein: In silico screening, stability, antihypertensive effects in vivo and underlying mechanisms

This study aimed to screen novel angiotensin I-converting enzyme (ACE) inhibitory peptides from garlic proteins and to explore their underlying antihypertensive mechanisms in vivo. After simulated hydrolysis and in silico screening, two novel peptides (MGR and HDCF) were obtained with the highest ACE inhibitory activity (IC50 of 4.50 μM and 26.38 μM) and acted as competitive inhibitors. They interacted with key residues in the ACE receptor mainly through hydrogen bonding and exhibited excellent stability against high temperature, extreme pH, and gastrointestinal digestion. In spontaneously hypertensive rats, MGR and HDCF effectively lowered blood pressure after single or continuous treatments. This was mainly achieved by balancing the renin-angiotensin system, improving renal and cardiac impairment, and regulating endothelial dysfunction. These findings suggested that garlic proteins were potentially suitable materials to prepare ACE inhibitory peptides and provided two promising candidates for ACE inhibition as functional food ingredients.

Milk and Its Derivatives as Sources of Components and Microorganisms with Health-Promoting Properties: Probiotics and Bioactive Peptides

Milk is a source of many valuable nutrients, including minerals, vitamins and proteins, with an important role in adult health. Milk and dairy products naturally containing or with added probiotics have healthy functional food properties. Indeed, probiotic microorganisms, which beneficially affect the host by improving the intestinal microbial balance, are recognized to affect the immune response and other important biological functions. In addition to macronutrients and micronutrients, biologically active peptides (BPAs) have been identified within the amino acid sequences of native milk proteins; hydrolytic reactions, such as those catalyzed by digestive enzymes, result in their release. BPAs directly influence numerous biological pathways evoking behavioral, gastrointestinal, hormonal, immunological, neurological, and nutritional responses. The addition of BPAs to food products or application in drug development could improve consumer health and provide therapeutic strategies for the treatment or prevention of diseases. Herein, we review the scientific literature on probiotics, BPAs in milk and dairy products, with special attention to milk from minor species (buffalo, sheep, camel, yak, donkey, etc.); safety assessment will be also taken into consideration. Finally, recent advances in foodomics to unveil the probiotic role in human health and discover novel active peptide sequences will also be provided.

Bioactivity-Guided Isolation and Antihypertensive Activity of Citrullus colocynthis Polyphenols in Rats with Genetic Model of Hypertension

Background and Objectives: Citrullus colocynthis belongs to the Cucurbitaceae family and is a wild medicinal plant used in folk literature to treat various diseases. The purpose of the current study was to explore the antihypertensive and antioxidant potentials of Citrullus colocynthis (CC) polyphenol-rich fractions using a spontaneous hypertensive rat (SHR) model. Materials and Methods: The concentrated aqueous ethanol extract of CC fruit was successively fractioned using solvents of increasing polarity, i.e., hexane, chloroform, ethyl acetate and n-butanol. The obtained extracts were analyzed for total phenolic content (TPC), total flavonoid content (TFC) and total flavonol content (TOF). Moreover, the CC extracts were further evaluated for radical scavenging capacity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays and antioxidant activity using inhibition of linoleic acid peroxidation and determination of reducing potential protocols. The phytochemical components were characterized by HPLC-MWD-ESI-MS in positive ionization mode. Results: The results showed that ethyl acetate fraction (EAF) exhibited a higher content of phenolic compounds in term of TPC (289 mg/g), TFC (7.6 mg/g) and TOF (35.7 mg/g). EAF showed higher antioxidant and DPPH and ABTS scavenging activities with SC50 values of 6.2 and 79.5 µg/mL, respectively. LCMS analysis revealed that twenty polyphenol compounds were identified in the EAF, including phenolic acids and flavonoids, mainly myricetin and quercetin derivatives. The in vivo antihypertensive activity of EAF of CC on SHR revealed that it significantly decreased the mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressures (DBP) and pulse pressure (PP) as compared to normal and hypertensive control groups. Moreover, EAF of CC significantly reduced the oxidative stress in the animals in a dose-dependent manner by normalizing the levels of superoxide dismutase (SOD), malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NOx) and total antioxidant capacity (TAC). Furthermore, the treatment groups, especially the 500 mg of EAF per kg body weight (EA-500) group, significantly (p ≤ 0.05) improved the electrocardiogram (ECG) pattern and pulse wave velocity (PWV). Conclusion: It was concluded that the EAF of CC is a rich source of polyphenols and showed the best antioxidant activity and antihypertensive potential in SHR.

Discovery of ACE Inhibitory Peptides Derived from Green Coffee Using In Silico and In Vitro Methods

Inhibition of angiotensin-I converting enzyme (ACE) is an important means of treating hypertension since it plays an important regulatory function in the renin-angiotensin system. The aim of this study was to investigate the ACE inhibitory effect of bioactive peptides from green coffee beans using in silico and in vitro methods. Alcalase and thermolysin were employed to hydrolyze protein extract from coffee beans. Bioactive peptides were identified by LC-MS/MS analysis coupled with database searching. The potential bioactivities of peptides were predicted by in silico screening, among which five novel peptides may have ACE inhibitory activity. In vitro assay was carried out to determine the ACE inhibitory degree. Two peptides (IIPNEVY, ITPPVMLPP) were obtained with IC50 values of 57.54 and 40.37 μM, respectively. Furthermore, it was found that two inhibitors bound to the receptor protein on similar sites near the S1 active pocket of ACE to form stable enzyme-peptide complexes through molecular docking, and the Lineweaver-Burk plot showed that IIPNEVY was a noncompetitive inhibitor, and ITPPVMLPP was suggested to be a mixed-type inhibitor. Our study demonstrated that two peptides isolated from coffee have potential applications as antihypertensive agents.

Nanoparticle approaches for the renin-angiotensin system

The renin-angiotensin system (RAS) is a hormonal cascade that contributes to several disorders: systemic hypertension, heart failure, kidney disease, and neurodegenerative disease. Activation of the RAS can promote inflammation and fibrosis. Drugs that target the RAS can be classified into 3 categories, AT1 angiotensin receptor blockers (ARBs), angiotensin-converting enzyme (ACE) inhibitors, and renin inhibitors. The therapeutic efficacy of current RAS-inhibiting drugs is limited by poor penetration across the blood-brain barrier, low bioavailability, and to some extent, short half-lives. Nanoparticle-mediated drug delivery systems (DDSs) are possible emerging alternatives to overcome such limitations. Nanoparticles are ideally 1-100 nm in size and are considered efficient DDSs mainly due to their unique characteristics, including water dispersity, prolonged half-life in blood circulation, smaller size, and biocompatibility. Nano-scale DDSs can reduce the drug dosage frequency and acute toxicity of drugs while enhancing therapeutic success. Different types of nanoparticles, such as chitosan, polymeric, and nanofibers, have been examined in RAS-related studies, especially in hypertension, cardiovascular disease, and COVID-19. In this review article, we summarize the physical and chemical characteristics of each nanoparticle to elaborate on their potential use in RAS-related nano-drug delivery research and clinical application.

Production and Characterization of ACE Inhibitory and Anti-Diabetic Peptides from Buffalo and Camel Milk Fermented with Lactobacillus and Yeast: A Comparative Analysis with In Vitro, In Silico, and Molecular Interaction Study

The investigation aimed at assessing a comparative study on the production and characterization of ACE inhibitory, anti-diabetic, and anti-inflammatory activities, along with the production of ACE inhibitory and anti-diabetic peptides through the fermentation of buffalo and camel milk by Limosilactobacillus fermentum (KGL4) and Saccharomyces cerevisiae (WBS2A). The angiotensin-converting enzyme (ACE) inhibitory and anti-diabetic properties were evaluated at particular time intervals (12, 24, 36, and 48 h) at 37 °C, and we discovered maximum activity at 37 °C after 48 h of incubation. The maximum ACE inhibitory, lipase inhibitory activities, alpha-glucosidase inhibitory, and alpha-amylase inhibitory activities were found in the fermented camel milk (77.96 ± 2.61, 73.85 ± 1.19, 85.37 ± 2.15, and 70.86 ± 1.02), as compared to the fermented buffalo milk (FBM) (75.25 ± 1.72, 61.79 ± 2.14, 80.09 ± 0.51, and 67.29 ± 1.75). Proteolytic activity was measured with different inoculation rates (1.5%, 2.0%, and 2.5%) and incubation times (12, 24, 36, and 48 h) to optimize the growth conditions. Maximum proteolysis was found at a 2.5% inoculation rate and at a 48 h incubation period in both fermented buffalo (9.14 ± 0.06) and camel milk (9.10 ± 0.17). SDS-PAGE and 2D gel electrophoresis were conducted for protein purification. The camel and buffalo milk that had not been fermented revealed protein bands ranging from 10 to 100 kDa and 10 to 75 kDa, respectively, whereas all the fermented samples showed bands ranging from 10 to 75 kDa. There were no visible protein bands in the permeates on SDS-PAGE. When fermented buffalo and camel milk were electrophoresed in 2D gel, 15 and 20 protein spots were detected, respectively. The protein spots in the 2D gel electrophoresis ranged in size from 20 to 75 kDa. To distinguish between different peptide fractions, water-soluble extract (WSE) fractions of ultrafiltration (3 and 10 kDa retentate and permeate) of fermented camel and buffalo milk were employed in RP-HPLC (reversed-phase high-performance liquid chromatography). The impact of fermented buffalo and camel milk on inflammation induced by LPS (lipopolysaccharide) was also investigated in the RAW 264.7 cell line. Novel peptide sequences with ACE inhibitory and anti-diabetic properties were also analyzed on the anti-hypertensive database (AHTDB) and bioactive peptide (BIOPEP) database. We found the sequences SCQAQPTTMTR, EMPFPK, TTMPLW, HPHPHLSFMAIPPK, FFNDKIAK, ALPMHIR, IPAVFK, LDQWLCEK, and AVPYPQR from the fermented buffalo milk and the sequences TDVMPQWW, EKTFLLYSCPHR, SSHPYLEQLY, IDSGLYLGSNYITAIR, and FDEFLSQSCAPGSDPR from the fermented camel milk.

Anti-Inflammatory, ACE Inhibitory, Antioxidative Activities and Release of Novel Antihypertensive and Antioxidative Peptides from Whey Protein Hydrolysate with Molecular Interactions

OBJECTIVE

The aim of the study was to evaluate the whey protein hydrolysate with bio-functional attributes viz. antioxidative, anti-inflammatory and ACE inhibition efficacy and release of bioactive peptides with antioxidative and ACE-inhibitory activity by employing Pepsin.

METHOD

The antioxidant, Anti-inflammatory, ACE inhibitory and proteolytic activities of the whey protein hydrolysates were studied followed by SDS-PAGE analysis and IEF. Anti-inflammatory activity of whey protein hydrolysate was also studied on RAW 264.7 cell line. The separation of the bioactive peptides from whey protein hydrolysate was achieved by RP-HPLC. The purified bioactive peptides were identified and characterized using RPLC/MS.

RESULTS

WPC (Whey protein concentrate) hydrolysate with pepsin showed proteolytic activity ranging between 14.46 and 18.87 mg/ml. Using the ABTS assay, the highest antioxidative activity was observed in 10 kDa retentate (84.50%) and 3 kDa retentate (85.96%), followed by the highest proteolytic activity (13.83 mg/ml) and ACE inhibitory activity (58.37%) in a 5% WPC solution at 65 °C after 8 h of pepsin hydrolysis. When the protein hydrolysate concentration was low, the production of proinflammatory cytokines by lipopolysaccharide-treated murine macrophages (RAW 264.7) was reduced. SDS-PAGE results exhibited very little protein bands when comparing with WPC hydrolysates to insoluble WPC. There were no protein spots on 2 D gel electrophoresis and "in-solution trypsin digestion" technique have been utilized to digest protein samples directly from WPC hydrolysates. Novel antioxidative peptides and ACE inhibitory peptides were also observed by comparing two databases, i.e., BIOPEP and AHTPDB respectively. The peptide sequences used in this study were found to have excellent potential to be used as inhibitors of hACE as all of them were able to show substantial interactions against the enzyme's active site.

CONCLUSIONS

The antihypertensive and antioxidative peptides from whey protein hydrolysates may be beneficial for the future development of physiologically active functional foods. Further, in vivo investigations are required to establish the health claim for each individual bioactive peptide from whey protein hydrolysate.

Supplemental data for this article is available online at.

Unlocking the bioactivity of meat proteins: Comparison of meat and meat hydrolysate via simulated gastrointestinal digestion

Understanding the functional attributes of meat proteins is crucial for determining their nutritional benefits. Depending on the form in which meat proteins are available, the digestive process can release peptides which are valuable for nutrition and may also possess bioactive properties, affecting physiology. Liquid chromatography - mass spectrometry (LC-MS) was used to quantitatively compare the molecular peptide features (representing non-redundant peptides), during the different stages of a simulated gastrointestinal digestion process of a minimally processed powdered meat and its enzymatically produced hydrolysate. Results from a principal component analysis (PCA) indicated that the hydrolysate did not undergo extensive additional digestion whereas the powdered meat was digested both at the gastric and in the intestinal phases. Bioactive peptide sequence prediction identified the meat hydrolysate but not the meat powder as the only source of exact and partial bioactive matches in the angiotensin-I converting enzyme and dipeptidyl peptidase IV inhibition categories. Also, a higher source of cryptides (encrypted bioactive peptides), indicated that meat hydrolysates are potentially a better substrate for the release of these enzyme inhibitory peptides. These observations thus suggest that pre-digestion of a complex food matrix such as meat, may enhance its bioavailability following oral consumption early in the digestion process. SIGNIFICANCE: This work highlights enzymatic hydrolysis of meat proteins prior to ingestion allows for potentially higher bioavailability of bioactive peptides that inhibit angiotensin-I converting enzyme and dipeptidyl peptidase IV, thus possibly aiding high blood pressure and type 2 diabetes management.

Peptidomic analysis of the angiotensin-converting-enzyme inhibitory peptides in milk fermented with Lactobacillus delbrueckii QS306 after ultrahigh pressure treatment

In this study, we assessed the effect of ultrahigh pressure (UHP) treatment on the concentration of peptides and angiotensin-converting enzyme (ACE) inhibitory activity in milk fermented with Lactobacillus delbrueckii QS306. The peptides were identified using peptidomic analysis, and 313 unique peptides were identified. These peptides were derived from 53 precursor proteins. Before and after UHP treatment, 361 (22.2%) peptide sequences exhibited difference, and 53 peptide segments were significantly different. Among them, small peptides (amino acid residues ≤6) isoelectric were point at pH 5-6, and the net charge was mainly positive or neutral. With hydrophobicity and ACE inhibitory activity as screening indicators, 214 small peptides with potential ACE inhibitory activity were identified, and 130 new peptides had potential ACE inhibitory activity. A novel ACE inhibitory peptide VAPFP was synthesized, whose in vitro inhibition rate was 10.56 μmol\/L. Therefore, using peptidomics, the changes in peptide sequences and enhancement in ACE inhibitory activity before and after UHP treatment could be effectively identified in milk fermented with Lactobacillus delbrueckii QS306. This study provided a convenient method for the discovery and identification of new ACE inhibitory peptides.

Separation and Purification of Antioxidant Peptide from Fermented Whey Protein by Lactobacillus rhamnosus B2-1

In this study, a antioxidant activity peptide fraction was separated and purified from metabolites of whey protein fermented by Lactobacillus rhamnosus B2-1. The fermentation sample was separated by macroporous resin D101 and Sephadex G-15. The collected fractions were tested for antioxidant and antitumor activities. In order to test the antioxidant activity of fractions, Hydroxyl (·OH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and Oxygen Radical Absorbance Capacity (ORAC) were used. The final purified peptide B11 showed highest ABTS and ·OH radical scavenging rate by 84.36±1.89% and 62.43±2.64%, respectively, and had an ORAC activity of 1,726.44± 2.76 μM Trolox equivalent/g. Further, the inhibitory effect of B11 on the proliferation of LoVo human colon cancer cells, KB and Cal-27 human oral cancer cells were enhanced with increasing concentrations of B11. B11 contains 51.421% amino acids, with Glu and Asp being the major constituents. In this study, we obtained peptide fraction B11 with antioxidant activity, which is promising for development.

Accurate Prediction of Anti-hypertensive Peptides Based on Convolutional Neural Network and Gated Recurrent unit

Hypertension (HT) is a general disease, and also one of the most ordinary and major causes of cardiovascular disease. Some diseases are caused by high blood pressure, including impairment of heart and kidney function, cerebral hemorrhage and myocardial infarction. Due to the limitations of laboratory methods, bioactive peptides for the treatment of HT need a long time to be identified. Therefore, it is of great immediate significance for the identification of anti-hypertensive peptides (AHTPs). With the prevalence of machine learning, it is suggested to use it as a supplementary method for AHTPs classification. Therefore, we develop a new model to identify AHTPs based on multiple features and deep learning. And the deep model is constructed by combining a convolutional neural network (CNN) and a gated recurrent unit (GRU). The unique convolution structure is used to reduce the feature dimension and running time. The data processed by CNN is input into the recurrent structure GRU, and important information is filtered out through the reset gate and update gate. Finally, the output layer adopts Sigmoid activation function. Firstly, we use Kmer, the deviation between the dipeptide frequency and the expected mean (DDE), encoding based on grouped weight (EBGW), enhanced grouped amino acid composition (EGAAC) and dipeptide binary profile and frequency (DBPF) to extract features. For Kmer, DDE, EBGW and EGAAC, it is widely used in the field of protein research. DBPF is a new feature representation method designed by us. It corresponds dipeptides to binary numbers, and finally obtains a binary coding file and a frequency file. Then these features are spliced together and input into our proposed model for prediction and analysis. After a tenfold cross-validation test, this model has a better competitive advantage than the previous methods, and the accuracy is 96.23% and 99.10%, respectively. From the results, compared with the previous methods, it has been greatly improved. It shows that the combination of convolution calculation and recurrent structure has a positive impact on the classification of AHTPs. The results show that this method is a feasible, efficient and competitive sequence analysis tool for AHTPs. Meanwhile, we design a friendly online prediction tool and it is freely accessible at http://ahtps.zhanglab.site/ .

Exploring the potential of Lacticaseibacillus paracasei M11 on antidiabetic, anti-inflammatory, and ACE inhibitory effects of fermented dromedary camel milk (Camelus dromedaries) and the release of antidiabetic and anti-hypertensive peptides

The goal of this investigation was to find antidiabetic peptides and inhibit angiotensin converting enzyme (ACE) in Lacticaseibacillus paracasei (M11) fermented dromedary camel milk (Camelus dromedaries). According to the findings, the rate of antidiabetic activity increased along with the incubation periods and reached its peak after 48 hr of fermentation. The inhibitions of α-amylase, α-glucosidase, and lipase were 80.75, 59.62, and 65.46%, respectively. The inhibitory activity of ACE was 78.33%, and the proteolytic activity was 8.90 mg/mL. M11 at 0.25 mg/mL effectively suppressed LPS-induced pro-inflammatory cytokines and their mediators such as NO, TNF-α, IL-6, and IL-1β in RAW 264.7 cells. The rate of inoculum in the optimization phase was 1.5-2.5%, and the greatest proteolytic activity was observed after 48 hr of fermentation. The investigation of the above property in the ultrafiltered fermented milk exhibited the highest antidiabetic and ACE inhibition activities in the 3 kDa than 10 kDa fractions. The molecular weight was determined employing SDS-PAGE, and the six-peptide sequences were identified using 2D gel electrophoresis. Due to its high proteolytic activity, the L. paracasei strain has been reported to be useful in the production of ACE-inhibitory and antidiabetic peptides. Amino acid sequences such from ɑ1, ɑ2, and β-caseins have been identified within fermented camel milk by searching on online databases, including BIOPEP (for antidiabetic peptides) and AHTPDB (for hypertension peptides) to validate the antidiabetic and ACE-inhibitory actions of several peptides. PRACTICAL APPLICATIONS: The study aims to identify antidiabetic peptides and inhibit ACE in dromedary camel milk fermented with Lacticaseibacillus paracasei M11. Maximum antidiabetic and ACE-inhibitory actions of the fermented camel milk were observed in 3 kDa permeate fractions. Fermented camel milk significantly reduced the excessive TNF-α, IL-6, and IL-1β production in LPS-activated RAW 264.7 cells. RP-LC/MS was used to identify 6 bioactive peptides from dromedary fermented camel milk. This fermented camel milk could be used for the management of hypertension and diabetic related problems.

Purification and Characterization of Novel Antihypertensive and Antioxidative Peptides From Whey Protein Fermentate: In Vitro, In Silico, and Molecular Interactions Studies

OBJECTIVE

The goal of this research was to purify and characterize the novel angiotensin-converting enzyme (ACE)-inhibitory and antioxidant peptides from fermented whey protein concentrate produced by Lactobacillus paracasei and Saccharomyces cerevisiae in a co-fermentation system.

METHOD

Whey protein fermented with lactic acid bacteria and yeast culture was analyzed for antioxidative, ACE inhibition, as well as anti-inflammatory activity followed by SDS-PAGE, isoelectric focusing, and 2-dimensional (2D) analysis. Anti-inflammatory activity of whey protein fermentate was also studied on the RAW 264.7 cell line. The bioactive peptides were separated from the whey protein fermentate using reverse-phase high-performance liquid chromatography (RP-HPLC) and reverse-phase liquid chromatography mass spectrometry (RPLC/MS), and thus identification and characterization of purified bioactive peptide was performed.

RESULTS

Whey protein fermentate samples' bioactivity was analyzed at specific time intervals at 12, 24, 36, and 48 hours at 37 °C for M11 and at 25 °C for WBS2A. The development settings (incubation time [12, 24, 36, and 48 hours) and inoculation rates [1.5%, 2.0%, and 2.5%]) were optimized for peptide synthesis via the o-phthaldialdehyde (OPA) method (proteolytic activity). Maximum proteolytic activity was observed at 37 °C for M11 (6.50 mg/mL) and at 25 °C for WBS2A (8.59 mg/mL) for 48 hours of incubation. Protein profiling was carried out using SDS-PAGE and 2D gel electrophoresis, in which Sodium dodecyl-sulfate (SDS) exhibited protein bands in the 10- to 55-kDa range, while 2D showed protein bands varying from 10 to 70 kDa. Every spot from 2D was digested by trypsin and identified by RPLC/MS. Protein fractionations (3- and 10-kDa permeates) were carried out employing RP-HPLC. Whey protein fermentate has anti-inflammatory action in RAW 264.7 macrophages that have been exposed to lipopolysaccharide. A molecular docking system was also used to investigate the interactions of peptides (AFLDSRTR, ILGAFIQIITFR) with human myeloperoxidase enzyme.

CONCLUSIONS

The antihypertensive and antioxidative peptides discovered from whey protein fermentate may be helpful in the design of pharmacologically active healthy ingredients in the upcoming years.

Inhibitory mechanism of angiotensin-converting enzyme inhibitory peptides from black tea

The aim of this work is to discover the inhibitory mechanism of tea peptides and to analyse the affinities between the peptides and the angiotensin-converting enzyme (ACE) as well as the stability of the complexes using in vitro and in silico methods. Four peptide sequences identified from tea, namely peptides I, II, III, and IV, were used to examine ACE inhibition and kinetics. The half maximal inhibitory concentration (IC₅₀) values of the four peptides were (210.03±18.29), (178.91±5.18), (196.31±2.87), and (121.11±3.38) μmol/L, respectively. The results of Lineweaver-Burk plots showed that peptides I, II, and IV inhibited ACE activity in an uncompetitive manner, which requires the presence of substrate. Peptide III inhibited ACE in a non-competitive manner, for which the presence of substrate is not necessary. The docking simulations showed that the four peptides did not bind to the active sites of ACE, indicating that the four peptides are allosteric inhibitors. The binding free energies calculated from molecular dynamic (MD) simulation were -72.47, -42.20, -52.10, and -67.14 kcal/mol (1 kcal=4.186 kJ), respectively. The lower IC₅₀ value of peptide IV may be attributed to its stability when docking with ACE and changes in the flexibility and unfolding of ACE. These four bioactive peptides with ACE inhibitory ability can be incorporated into novel functional ingredients of black tea.

ACE Inhibitory Peptides from Bellamya bengalensis Protein Hydrolysates: In Vitro and In Silico Molecular Assessment

Bellamya bengalensis muscle meat is known for ethnopharmacological benefits. The present study focuses on the identification of ACE inhibitory peptides from the proteolytic digests of muscle protein of Bellamya bengalensis and its underlying mechanism. After ultrafiltration of 120 min alcalase hydrolysates (BBPHA120) to isolate the small peptide fraction (<3 kDa), in vitro ACE inhibitory activity was analyzed. The IC50 value of the 120 min hydrolysate ultrafiltered fraction was 86.74 ± 0.575 µg/mL, while the IC50 of lisinopril was 0.31 ± 0.07 µg/mL. This fraction was assessed in a MALDI-ToF mass spectrometer and five peptides were identified from the mass spectrum based on their intensity (>1 × 104 A.U.). These peptides were sequenced via de novo sequencing. Based on the apparent hydrophobicity (%), the IIAPTPVPAAH peptide was selected for further analysis. The sequence was commercially synthesized by solid-phase standard Fmoc chemistry (purity 95–99.9%; by HPLC). The synthetic peptide (IC50 value 8.52 ± 0.779 µg/mL) was used to understand the thermodynamics of the inhibition by checking the binding affinity of the peptide to ACE by isothermal titration calorimetry compared with lisinopril, and the results were further substantiated by in silico site-specific molecular docking analysis. The results demonstrate that this peptide sequence (IIAPTPVPAAH) can be used as a nutraceutical with potent ACE inhibition.

Dairy-originated digestion-resistant and bioactive peptides increase the risk of hypertension: Tehran Lipid and Glucose Study

Milk-protein-derived bioactive peptides (BPs) have been proposed as modulators of different regulatory processes involved in blood pressure regulation. Studies on the long-term effects of BPs on blood pressure have not yet been conducted. We aimed to investigate the association of dairy-originated BPs with the risk of hypertension (HTN) in the Tehran Lipid and Glucose Cohort Study (TLGS). In this cohort study, 4378 subjects with a mean follow-up period of 3.1 years were included in the final analysis. Dietary intake, physical activity, demographic, and anthropometric data and blood pressure measurements were obtained for all participants. Various types of dairy-originated BPs were determined by an in silico method. High intake of total digestion-resistant and bioactive peptides (OR: 1.31, CI 95%: 1.01-1.70), dipeptides (OR: 1.33, CI 95%: 1.03-1.73), peptides with more than seven residues (OR: 1.32, CI 95%: 1.01-1.71), glycosylated residues (OR: 1.39, CI 95%: 1.07-1.80), highly hydrophilic peptides (OR: 1.32, CI 95%: 1.01-1.71), and low hydrophobic peptides (OR: 1.32, CI 95%: 1.01-1.71) was associated with an increased risk of HTN in the adjusted model. In addition, subjects in the higher tertile of anti-HTN peptide (OR: 1.33, CI 95%: 1.02-1.72) and antidiabetic peptide (OR: 1.35, CI 95%: 1.04-1.76) intake had a higher risk of HTN than those in the lower tertile. No significant association emerged between calcium intake from dairy and incident risk of HTN. Our results showed that the intake of some forms of digestion-resistant and BPs, such as anti-HTN peptides, dipeptides, and peptides with more than seven residues, can increase the risk of HTN in the TLGS population.

SAPdb: A database of short peptides and the corresponding nanostructures formed by self-assembly

Nanostructures generated by self-assembly of peptides yield nanomaterials that have many therapeutic applications, including drug delivery and biomedical engineering, due to their low cytotoxicity and higher uptake by targeted cells owing to their high affinity and specificity towards cell surface receptors. Despite the promising implications of this rapidly expanding field, there is no dedicated resource to study peptide nanostructures. This study endeavours to create a repository of short peptides, which may prove to be the best models to study ordered nanostructures formed by peptide self-assembly. SAPdb has a repertoire of 1049 entries of experimentally validated nanostructures formed by the self-assembly of small peptides. It consists of 328 tripeptides, 701 dipeptides, and 20 single amino acids with some conjugate partners. Each entry encompasses comprehensive information about the peptide, such as chemical modifications, the type of nanostructure formed, experimental conditions like pH, temperature, solvent required for the self-assembly, etc. Our analysis indicates that peptides containing aromatic amino acids favour the formation of self-assembling nanostructures. Additionally, we observed that these peptides form different nanostructures under different experimental conditions. SAPdb provides this comprehensive information in a hassle-free tabulated manner at a glance. User-friendly browsing, searching, and analysis modules have been integrated for easy data retrieval, data comparison, and examination of properties. We anticipate SAPdb to be a valuable repository for researchers engaged in the burgeoning arena of nanobiotechnology. It is freely available at https://webs.iiitd.edu.in/raghava/sapdb.

A specific selenium-chelating peptide isolated from the protein hydrolysate of Grifola frondosa

Background: Grifola frondosa is a type of edible medicinal mushroom with abundant proteins. Selenium (Se) is an essential micronutrient for human. Many animal experiments and clinical studies had indicated that Se plays an important role in diverse physiologic actions. Most inorganic selenium compounds are toxic, and the lowest lethal dose is relatively small. Peptide-Se chelate can probably be dietary supplements in functional foods for humans with Se deficiency. Methods: In this study, a specific tripeptide Arg-Leu-Ala (RLA) with strong Se-chelating capacity was purified from Grifola frondosa through ultrafiltration, reversed-phase HPLC and gel filtration chromatography. The UV, SEM, XRD, 1H NMR spectra are shown to provide more information about characterization of RLA-Se chelates. The bioavailability of RLA-Se chelate in Caco-2 cell line was investigated by using human colon cancer Caco-2 cells as model. iTRAQ comparative proteomics approach were used to identify the differentially expressed proteins. Results: The Se binding capacity of RLA was 84.47 ± 1.21 mg g-1. The results of UV, X-ray diffraction (XRD), 1H NMR and SEM structure analysis showed that the binding of selenium in the hydrolysate of Grifola frondosa protein was successful, and the amino and carboxyl groups of RLA were involved in the coordination of Se, which was the main site of chelation. The results of absorption of RLA-Se chelate in Caco-2 cells showed that RLA-Se chelate could be used as selenium supplement source. Using iTRAQ comparative proteomics approach, 40 proteins found significant. RLA-Se treatment had been demonstrated to present a higher accumulation of Se compared with control treatment and show an effective absorption by Caco-2 with the result that E3 protein performed up regulation. RLA-Se may play roles in cell cycle and apoptosis as an essential micronutrient. To sum up, our research results show that Grifola polypeptide-Se chelate is a promising multifunctional organic selenium product, which can be used as a new functional supplement for selenium deficiency.

The Effects of Processing and Preservation Technologies on Meat Quality: Sensory and Nutritional Aspects

This review describes the effects of processing and preservation technologies on sensory and nutritional quality of meat products. Physical methods such as dry aging, dry curing, high pressure processing (HPP), conventional cooking, sous-vide cooking and 3D printing are discussed. Chemical and biochemical methods as fermentation, smoking, curing, marination, and reformulation are also reviewed. Their technical limitations, due to loss of sensory quality when nutritional value of these products is improved, are presented and discussed. There are several studies focused either on the nutritional or sensorial quality of the processed meat products, but more studies with an integration of the two aspects are necessary. Combination of different processing and preservation methods leads to better results of sensory quality; thus, further research in combinations of different techniques are necessary, such that the nutritional value of meat is not compromised.

Pulses' germination and fermentation: Two bioprocessing against hypertension by releasing ACE inhibitory peptides

Angiotensin-Converting Enzyme (ACE) is one of the main blood pressure regulators in the renin-angiotensin system leading to hypertension. Hypertension is known as the modern world disease which increases the risk of serious human health problems. Synthetic drugs and some natural compounds could treat this disease by binding to ACE and reducing its activity. Pulses, one of the legumes group, that are the rich in protein sources in the human diet, have several bioactive compounds with ACE inhibitory (ACE I) properties. However, several processes need to break down proteins and improve ACE I activity in foods. Germination and fermentation, known by bioprocessing, could make releasing bioactive peptides and polyphenols and exhibit ACE I and either other health properties such as antimicrobial, antioxidant, anti-diabetic and anticancer activities. Various factors such as kind of selective culture, temperature, time and humidity affect these processes. This review summarizes relevant studies about the effect of pulses' germination and fermentation to produce ACE I activity compounds and also explains about main parameters affecting the health properties of these two bioprocessing to treat hypertension that could lead to the development of their application in pharmaceuticals instead of synthetic drugs.

mAHTPred: a sequence-based meta-predictor for improving the prediction of anti-hypertensive peptides using effective feature representation

MOTIVATION

Cardiovascular disease is the primary cause of death globally accounting for approximately 17.7 million deaths per year. One of the stakes linked with cardiovascular diseases and other complications is hypertension. Naturally derived bioactive peptides with antihypertensive activities serve as promising alternatives to pharmaceutical drugs. So far, there is no comprehensive analysis, assessment of diverse features and implementation of various machine-learning (ML) algorithms applied for antihypertensive peptide (AHTP) model construction.

RESULTS

In this study, we utilized six different ML algorithms, namely, Adaboost, extremely randomized tree (ERT), gradient boosting (GB), k-nearest neighbor, random forest (RF) and support vector machine (SVM) using 51 feature descriptors derived from eight different feature encodings for the prediction of AHTPs. While ERT-based trained models performed consistently better than other algorithms regardless of various feature descriptors, we treated them as baseline predictors, whose predicted probability of AHTPs was further used as input features separately for four different ML-algorithms (ERT, GB, RF and SVM) and developed their corresponding meta-predictors using a two-step feature selection protocol. Subsequently, the integration of four meta-predictors through an ensemble learning approach improved the balanced prediction performance and model robustness on the independent dataset. Upon comparison with existing methods, mAHTPred showed superior performance with an overall improvement of approximately 6-7% in both benchmarking and independent datasets.

AVAILABILITY AND IMPLEMENTATION

The user-friendly online prediction tool, mAHTPred is freely accessible at http://thegleelab.org/mAHTPred.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Purification and characterization of antioxidant peptides from enzymatic hydrolysate of mungbean protein

In this study, the antioxidant activity of mungbean protein hydrolysate (MPH) was systematically investigated. MPH was fractionated by ultrafiltration into two major fractions (MPH-1 <3 kDa, MPH-2 >3 kDa). Fraction MPH-1, which exhibited the highest antioxidant activity, was further fractionated by gel column into three fractions (MPH-1A, MPH-1B, and MPH-1C). The antioxidant activity of the MPH-1B fraction was stronger than that of the other fractions. Eight mungbean peptides (P1-P8) were identified in fraction MPH-1B by UPLC-Q-TOF-MS. Among them, peptides Trp-Gly-Asn (WGN, P2), Ala-Trp (AW, P4), Arg-Gly-Trp-Tyr-Glu (RGWYE, P5), and Gly-Val-Pro-Phe-Trp (GVPFW, P7) had high antioxidant activity. Moreover, these four peptides exerted protective effects against H₂ O₂ -induced cytotoxicity and regulated the MDA content, CAT activity, and total GSH content in HepG2 cells with specific observation. This study demonstrated the potential of MPH as a source of antioxidant peptides. This provides a scientific basis for the preparation of antioxidant peptides from mungbean protein. PRACTICAL APPLICATION: This study demonstrated the potential of the hydrolysate of mungbean protein as a source of antioxidant peptides and provided a scientific basis for the preparation of antioxidant peptides from mungbean protein.

Toxin to medicine and bioisosterism in drug development: a study of the discovery and development of ACE inhibitors from snake venom

The advent of the angiotensin-converting enzyme (ACE) inhibitors is a landmark in drug discovery and a breakthrough in the management of hypertension. Their clinical introduction has led to appreciable increase in the lifespan of hypertensive patients. And their development initiated a new era of structure-based or rational drug design that has subsequently been applied successfully for development of drugs for many other disorders. This paper presents an account of the discovery, design and development of ACE inhibitors from an academic perspective and possibly, as a guide to future research. The paper highlights the milestones and recounts the challenges encountered and the strategies applied in the search for ACE inhibitors. This exposition also expounds some of the concepts and intricacies of drug discovery, design and development. Keywords: drug development, ACE inhibitors, snake venom peptide, bioisosterism, antihypertensive agents

The Health-Promoting Potential of Salix spp. Bark Polar Extracts: Key Insights on Phenolic Composition and In Vitro Bioactivity and Biocompatibility

Salix spp. have been exploited for energy generation, along with folk medicine use of bark extracts for antipyretic and analgesic benefits. Bark phenolic components, rather than salicin, have demonstrated interesting bioactivities, which may ensure the sustainable bioprospection of Salix bark. Therefore, this study highlights the detailed phenolic characterization, as well as the in vitro antioxidant, anti-hypertensive, Staphylococcus aureus growth inhibitory effects, and biocompatibility of Salix atrocinerea Brot., Salix fragilis L., and Salix viminalis L. bark polar extracts. Fifteen phenolic compounds were characterized by ultra-high-performance liquid chromatography-ultraviolet detection-mass spectrometry analysis, from which two flavan-3-ols, an acetophenone, five flavanones, and a flavonol were detected, for the first time, as their bark components. Salix bark extracts demonstrated strong free radical scavenging activity (5.58–23.62 µg mL⁻¹ IC₅₀ range), effective inhibition on angiotensin-I converting enzyme (58–84%), and S. aureus bactericidal action at 1250–2500 µg mL⁻¹ (6–8 log CFU mL⁻¹ reduction range). All tested Salix bark extracts did not show cytotoxic potential against Caco-2 cells, as well as S. atrocinerea Brot. and S. fragilis L. extracts at 625 and 1250 µg mL⁻¹ against HaCaT and L929 cells. These valuable findings can pave innovative and safer food, nutraceutical, and/or cosmetic applications of Salix bark phenolic-containing fractions.

Isolation and Characterization of Angiotensin Converting Enzyme Inhibitory Peptides from Peach Seed Hydrolysates: In Vivo Assessment of Antihypertensive Activity

A peptide fraction with molecular masses below 3 kDa (PSH-3 kDa) from a peach seed hydrolysate demonstrated high angiotensin converting enzyme (ACE) inhibitory activity (concentration to inhibit 50% ACE (IC₅₀) = 16.4 μg/mL) in our previous work. This work proposes a further study of this highly active fraction. RP-HPLC enabled two fractions (F3 and F4) with high inhibitory activity (IC₅₀ = 2.0 ± 0.5 and 1.2 ± 0.2 μg/mL, respectively) to be isolated. Peptide analysis by LC-Q-TOF-MS/MS using reverse-phase and hydrophilic interaction chromatography enabled 33 peptides within both fractions to be identified. Among them, peptide isoleucine-tyrosine-serine-proline-histidine (IYSPH) showed the highest capacity. The lack of cytotoxicity of peptides was demonstrated in three different cell lines (HeLa, HT-29, and HK-2). Oral administration of PSH-3 kDa fraction or peptide IYSPH caused a significant systolic blood pressure reduction (-30 mmHg) on spontaneously hypertensive rats after 3-6 h treatment.

Purification and Characterization of Antioxidant Peptides from Alcalase-Hydrolyzed Soybean ( Glycine max L.) Hydrolysate and Their Cytoprotective Effects in Human Intestinal Caco-2 Cells

This study aimed to purify and identify antioxidant peptides from the low-molecular-weight fraction (SPH-I, MW < 3 kDa) of Alcalase-hydrolyzed soybean ( Glycine max L.) hydrolysate and further evaluate the cytoprotective effects of synthesized peptides against oxidative stress in human intestinal Caco-2 cells. After purification by gel filtration chromatography and reversed-phase HPLC, four major peptides were sequenced by nano-LC-ESI-MS/MS as VVFVDRL (847 Da, SPH-IA), VIYVVDLR (976 Da, SPH-IB), IYVVDLR (877 Da, SPH-IC), and IYVFVR (795 Da, SPH-ID). The antioxidant peptides were synthesized and displayed desirable DPPH radical-scavenging activity (from 16.5 ± 0.5 to 20.3 ± 1.0 μM Trolox equivalent (TE)/μM), ABTS•+ radical-scavenging activity (from 3.42 ± 0.2 to 4.24 ± 0.4 mM TE/μM), ORAC (from 143 ± 2.1 to 171 ± 4.8 μM TE/μM), and FRAP (from 54.7 ± 1.2 to 79.0 ± 0.6 mM Fe2+/μM). Moreover, the synthesized peptides protected Caco-2 cells against H2O2-induced oxidative damage via significantly downregulating intracellular ROS generation and lipid peroxidation ( p < 0.05). Additionally, SPH-IC and SPH-ID statistically upregulated total reduced glutathione synthesis, enhanced activities of catalase and glutathione reductase, and suppressed ROS-mediated inflammatory responses via inhibiting interleukin-8 secretion ( p < 0.05).

Isolation and Characterization of Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptides from the Enzymatic Hydrolysate of Carapax Trionycis (the Shell of the Turtle Pelodiscus sinensis)

Carapax Trionycis (the shell of the turtle Pelodiscus sinensis) was hydrolyzed by six different commercial proteases. The hydrolysate prepared from papain showed stronger inhibitory activity against angiotensin I-converting enzyme (ACE) than other extracts. Two noncompetitive ACE inhibitory peptides were purified successively by ultrafiltration, gel filtration chromatography, ion exchange column chromatography, and high-performance liquid chromatography (HPLC). The amino acid sequences of them were identified as KRER and LHMFK, with IC₅₀ values of 324.1 and 75.6 μM, respectively, confirming that Carapax Trionycis is a potential source of active peptides possessing ACE inhibitory activities. Besides, both enzyme kinetics and isothermal titration calorimetry (ITC) assay showed that LHMFK could form more stable complex with ACE than KRER, which is in accordance with the better inhibitory activity of LHMFK.

Physicochemical and sensory properties of yogurts containing sacha inchi (Plukenetia volubilis L.) seeds and β-glucans from Ganoderma lucidum

Dairy products have been widely used for adding various biomolecules with the aim of improving their functional properties and health benefits. In this study, the physicochemical properties and sensory acceptance of yogurts enriched with sacha inchi (Plukenetia volubilis) seeds (SIS) and β-glucans from Ganoderma lucidum (BGGL) were investigated. The angiotensin-converting enzyme-inhibitory activity of some yogurt samples was also evaluated. Yogurts were produced from reconstituted skim milk powder, and SIS (4% wt/wt) and BGGL were added at different concentrations (0-1.5% wt/wt). The fermentation kinetics were not affected by the enrichment process. The addition of SIS and BGGL significantly increased the contents of protein, fat, carbohydrates, ash, total solids, aspartic acid, serine, arginine, glycine, threonine, tyrosine, and alanine. α-Linolenic (49.3%) and linoleic (32.2%) acids were the main fatty acids found in the enriched samples, whose values were about 50- and 25-fold higher than those of the control yogurt. The textural parameters (firmness, consistency, cohesiveness, and index of viscosity) of the enriched yogurts were significantly lower than those of the control samples during the whole storage period. All enriched yogurts showed a sensorial acceptance higher than 70% by untrained panelists. The angiotensin-converting enzyme-inhibitory activity of some selected yogurt samples ranged between 36 and 59%. These results indicate that SIS and BGGL could be used as natural ingredients for improving the nutritional value of yogurt and fermented milks.

Identification of Potent ACE Inhibitory Peptides from Wild Almond Proteins

In this study, the production, fractionation, purification and identification of ACE (angiotensin-I-converting enzyme) inhibitory peptides from wild almond (Amygdalus scoparia) proteins were investigated. Wild almond proteins were hydrolyzed using 5 different enzymes (pepsin, trypsin, chymotrypsin, alcalase and flavourzyme) and assayed for their ACE inhibitory activities. The degree of ACE inhibiting activity obtained after hydrolysis was found to be in the following order: alcalase > chymotrypsin > trypsin/pepsin > flavourzyme. The hydrolysates obtained from alcalase (IC₅₀ = 0.8 mg/mL) were fractionated by sequential ultrafiltration at 10 and 3 kDa cutoff values and the most active fraction (<3 kDa) was further separated using reversed phase high-performance liquid chromatography (RP-HPLC). Peptide sequence identifications were carried out on highly potential fractions obtained from RP-HPLC by means of liquid chromatography coupled to electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS). Sequencing of ACE inhibitory peptides present in the fraction 26 of RP-HPLC resulted in the identification of 3 peptide sequences (VVNE, VVTR, and VVGVD) not reported previously in the literature. Sequence identification of fractions 40 and 42 from RP-HPLC, which showed the highest ACE inhibitory activities (84.1% and 86.9%, respectively), resulted in the identification of more than 40 potential ACE inhibitory sequences. The results indicate that wild almond protein is a rich source of potential antihypertensive peptides and can be suggested for applications in functional foods and drinks with respect to hindrance and mitigation of hypertension after in vivo assessment.

PRACTICAL APPLICATION

This study has shown the potential of wild almond proteins as good sources for producing ACE-inhibitory active peptides. According to this finding, peptides with higher ACE inhibitory activities could be released during the gastrointestinal digestion and contribute to the health- promoting activities of this natural protein source.

STRUCTURAL CHARACTERISTICS AND ANTIHYPERTENSIVE EFFECTS OF ANGIOTENSIN-I-CONVERTING ENZYME INHIBITORY PEPTIDES IN THE RENIN-ANGIOTENSIN AND KALLIKREIN KININ SYSTEMS

BACKGROUND

The commercially available synthetic angiotensin-I-converting enzyme (ACE) inhibitors are known to exert negative side effects which have driven many research groups globally to discover the novel ACE inhibitors.

METHOD

Literature search was performed within the PubMed, ScienceDirect.com and Google Scholar.

RESULTS

The presence of proline at the C-terminal tripeptide of ACE inhibitor can competitively inhibit the ACE activity. The effects of other amino acids are less studied leading to difficulties in predicting potent peptide sequences. The broad specificity of the enzyme may be due to the dual active sites observed on the somatic ACE. The inhibitors may not necessarily competitively inhibit the enzyme which explains why some reported inhibitors do not have the common ACE inhibitor characteristics. Finally, the in vivo assay has to be carried out before the peptides as the antihypertensive agents can be claimed. The peptides must be absorbed into circulation without being degraded, which will affect their bioavailability and potency. Thus, peptides with strong in vitro IC50 values do not necessarily have the same effect in vivo and vice versa.

CONCLUSION

The relationship between peptide amino acid sequence and inhibitory activity, in vivo studies of the active peptides and bioavailability must be studied before the peptides as antihypertensive agents can be claimed.

Selective separation and concentration of antihypertensive peptides from rapeseed protein hydrolysate by electrodialysis with ultrafiltration membranes

Rapeseed protein isolate was subjected to alcalase digestion to obtain a protein hydrolysate that was separated into peptide fractions using electrodialysis with ultrafiltration membrane (EDUF) technology. The EDUF process (6h duration) led to isolation of three peptide fractions: anionic (recovered in KCl-1 compartment), cationic (recovered in KCl-2 compartment), and those that remained in the feed compartment, which was labeled final rapeseed protein hydrolysate (FRPH). As expected the KCl-1 peptides were enriched in negatively-charged (43.57%) while KCl-2 contained high contents of positively-charged (28.35%) amino acids. All the samples inhibited angiotensin converting enzyme (ACE) and renin activities in dose-dependent manner with original rapeseed protein hydrolysate having the least ACE-inhibitory IC50 value of 0.0932±0.0037 mg/mL while FRPH and KCl-2 had least renin-inhibitory IC50 values of 0.47±0.05 and 0.55±0.06 mg/mL, respectively. Six hours after oral administration (100 mg/kg body weight) to spontaneously hypertensive rats, the FRPH produced the maximum systolic blood pressure reduction of -51 mmHg.

A Novel Peptide from Soybean Protein Isolate Significantly Enhances Resistance of the Organism under Oxidative Stress

Recent studies have indicated that protein hydrolysates have broad biological effects. In the current study we describe a novel antioxidative peptide, FDPAL, from soybean protein isolate (SPI). The aim of this study was to purify and characterize an antioxidative peptide from SPI and determine its antioxidative mechanism. LC–MS/MS was used to isolate and identify the peptide from SPI. The sequence of the peptide was determined to be Phe-Asp-Pro-Ala-Leu (FDPAL, 561 Da). FDPAL can cause significant enhancement of resistance to oxidative stress both in cells as well as simple organisms. In Caenorhabditis elegans (C. elegans), FDPAL can up-regulate the expression of certain genes associated with resistance. The antioxidant activity of this peptide can be attributed to the presence of a specific amino acid sequence. Results from our work suggest that FDPAL can facilitate potential applications of proteins carrying this sequence in the nutraceutical, bioactive material and clinical medicine areas, as well as in cosmetics and health care products.

Gut microbiome and metabolic syndrome

The gut microbiome contributes approximately 2kg of the whole body weight, and recent studies suggest that gut microbiota has a profound effect on human metabolism, potentially contributing to several features of the metabolic syndrome. Metabolic syndrome is defined by a clustering of metabolic disorders that include central adiposity with visceral fat accumulation, dyslipidemia, insulin resistance, dysglycemia and non-optimal blood pressure levels. Metabolic syndrome is associated with an increased risk of cardiovascular diseases and type 2 diabetes. It is estimated that around 20-25 percent of the world's adult population has metabolic syndrome. In this manuscript, we have reviewed the existing data linking gut microbiome with metabolic syndrome. Existing evidence from studies both in animals and humans support a link between gut microbiome and various components of metabolic syndrome. Possible pathways include involvement with energy homeostasis and metabolic processes, modulation of inflammatory signaling pathways, interferences with the immune system, and interference with the renin-angiotensin system. Modification of gut microbiota via prebiotics, probiotics or other dietary interventions has provided evidence to support a possible beneficial effect of interventions targeting gut microbiota modulation to treat components or complications of metabolic syndrome.